1. Field of the Invention
This invention relates to a film-forming preparation for protection against infections which is particularly suitable for protecting teats and udders of cattle, sheep and goats against infections after milking.
Nowadays, cattle, sheep and goats are mainly milked by automatic milking techniques. The animals, which have been bred over many years for high milk production, are extremely susceptible to infection in the region of their mammary glands and udders. This susceptibility to infection is increased by the heavy stressing which the teats undergo during milking and by environmental factors to which the teats are constantly exposed, such as wind, rain and sunshine.
As a result of this constant stressing of their teats, the animals frequently develop udder inflammations which are described in the literature as "subclinical" or "clinical" mastitis. Depending on the level of infection of the affected part of the udder, there is a slight to drastic increase in somatic cells in the milk. The increase in somatic cells in the milk beyond the level of healthy udders (200,000 cells per ml) is undesirable because it affects the quality of the milk for the subsequent processing steps or, in extreme cases, makes the milk unfit for consumption. A drastic increase in somatic cells in the milk is often accompanied by fever (clinical mastitis) and can even result in the loss of the animal through enforced slaughter.
One of the causes of such infections is the penetration of udder-pathogenic bacteria such as, for example, Pseudomonas aeruginosa, Escherichia coli, Streptococcus uberis, Streptococcus dysagalactiae, Streptococcus agalactiae, Staphylococcus aureus, Enterococcus hirae.
The risk of udder infection is at its greatest immediately after milking when the nipple duct is open so that bacteria from the environment around the udder are able to migrate into the nipple duct and to cause infections.
In order to avoid or reduce the risk of infection, the teats of the milked animals are treated with udder "dips" after each milking. The treatment is carried out either by dipping the teats in or spraying them with the disinfecting solution. As a result of this measure, the bacteria present on the udder/teat skin are destroyed in 10 minutes, thus reducing the risk of infection through the open nipple duct.
Unfortunately, the disadvantage of using udder dips is that the nipple duct is open for up to 60 minutes after milking. However, commercial dips are of such low viscosity that they mechanically close the nipple duct for only a short time (about 10 minutes) by forming droplets at the ends of the teats. This protection of the teats is removed again after a short time by drying of the preparation in the air or by rubbing off of the preparation from the ends of the teats when the animals lie down. Accordingly, the teats are again susceptible to infection by pathogenic bacteria through the open nipple duct. Another disadvantage of known products lies in the very high concentration of disinfecting agent in the preparations which is required to achieve a disinfecting effect in the short contact time described.
2. Discussion of Related Art
Concentrations of free iodine of 2,500 to 10,000 ppm are normally used to achieve adequate germ destruction levels (3.0 log stages) on the udder/teat skin. Iodine concentrations as high as these lead to a corresponding increase in the iodine content of the milk which should be avoided in the interests of human health.
Further disadvantages of such preparations lie in the use of nonylphenol ethoxylates as iodine carriers (nonoxinol iodine). Earlier toxicological studies point to the risk to health posed by nonoxinols as a residue in foods. The danger of "myocordial necroses" is described in the studies of Smith and Calandra (Toxicological Studies of Alkylphenol Polyoxyethylene Surfactants--Toxicology and Applied Pharmacology 14, 315-334, 1969). The latest toxicological discussions relate to the estrogenic effects of such substances (Bundestagsdrucksache 13/3181-13, Wahlperiode//Environmental Toxicology and Chemistry, Vol. 15, No. 3, pp 241-248, 1996, Setac//CEFIC Press Statement "Environmental Estrogen and Endocrine Modulators", Apr. 29, 1996).
For example, EP-A-90 205 describes an udder care and teat disinfecting preparation for dairy cattle which is formulated for application as a high-viscosity aqueous emulsion and which contains inter alia 800 to 1,200 ppm of iodine in the form of a disinfecting iodine complex. Adducts of iodine with polyglycol ethers or with polyvinyl pyrrolidone may be used as the disinfecting iodine complex.
WO 94/23581 describes teat disinfectants which are free from many of the disadvantages mentioned above. They contain a film-forming component consisting of polyvinyl alcohol, a polymeric thickener and an antimicrobial nonionic iodine complex. The nonionic iodine complex may be selected, for example, from adducts of iodine with polyethylene glycol, polypropylene glycol or copolymers thereof. Alcoholates, phenolates and carboxylates may be used as polymerization initiating molecules. According to the Examples, nonylphenol ethoxylates are used as iodine carriers.
The problem addressed by the present invention was to provide a film-forming preparation for protecting the teats and udders of dairy cattle against infection which would not require the ecologically and toxicologically unsafe nonylphenol ethoxylates. Suitable toxicologically favorable alternatives are, on the one hand, chlorhexidine and, on the other hand, iodine in the form of polyvinyl pyrrolidone iodine. However, if an attempt is made to replace the nonylphenol ethoxylate iodine in the film formers according to WO 94/23581 by these more favorable disinfecting agents, either firmly adhering films which cannot be removed in a reasonable time are obtained, depending on the formulation, or the films remain moist and tacky so that they are either rubbed off or lead to heavily soiled udders by attracting dirt when the cattle lie down. Accordingly, another problem addressed by the invention was to provide an alternative film-forming preparation that would form firmly adhering, dry films which would protect the teat skin and which would be able to be removed in a short time, for example in about 10 to about 60 seconds, by exposure to moisture.